Worn banknote identification method and atm using the same

ABSTRACT

The present disclosure relates to a worn banknote identification method and an ATM (Automated Teller Machine) using the same, and more particularly, to a worn banknote identification method which acquires an image of a banknote inserted into an ATM, divides pixels of the acquired banknote image into a bright region and dark region depending on a brightness distribution of the banknote image, determines the wear level of the banknote by comparing a difference between the average brightness values of the two regions to a preset reference value, and separately stores the inserted banknote into a reject box depending on the wear level of the banknote, and an ATM using the same.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Republic of Korea Patent ApplicationNo. 10-2016-0095279 filed on Jul. 27, 2016, which is incorporated byreference herein in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a worn banknote identification methodand an ATM (Automated Teller Machine) using the same, and moreparticularly, to a worn banknote identification method which acquires animage of a banknote inserted into an ATM, divides pixels of the acquiredbanknote image into a bright region and dark region depending on abrightness distribution of the banknote image, determines the wear levelof the banknote by comparing a difference between the average brightnessvalues of the two regions to a preset reference value, and separatelystores the inserted banknote into a reject box depending on the wearlevel of the banknote, and an ATM using the same.

2. Related Art

ATM (Automated Teller Machine) represents an automated device that canassist a basic financial service such as deposit or withdrawal without abank teller, regardless of time and place in connection with financialservices. The ATM enables a customer to conduct a transaction such aswithdrawal or deposit of cash through his operation using a medium suchas a card or bankbook.

Recently, most companies have a five-day workweek. Thus, more and morepeople use an ATM or CD (Cash Dispenser) rather than personally go tobank. Therefore, the installation of the ATM has gradually spread, andthe number of ATMs has gradually increased. The recent ATMs areimplemented in consideration of various additional functions as well asmain tasks. Continuously, various ATMs are being developed in order toimprove bank competitiveness while satisfying customers' satisfactions.

Typically, an ATM includes an identification unit for identifying thekinds of banknotes inserted by customers and determining whether thebanknotes are counterfeit banknotes and/or whether the banknotes aredamaged. The ATM classifies the inserted banknotes according to theidentification results of the identification unit, and stores theclassified banknotes into the corresponding cassettes.

FIG. 1 is a diagram illustrating a conventional ATM.

As illustrated in FIG. 1, the conventional ATM includes: adeposit/withdrawal unit 1 through which a customer inserts or receivesbanknotes for deposit or withdrawal; a transfer path 2 through which thebanknotes deposited/withdrawn through the deposit/withdrawal unit 1 aretransferred; a medium determination unit 3 installed on the transferpath 2 so as to determine whether the transferred banknotes are normal;a temporary storage unit 4 for temporarily storing the banknotes passedthrough the medium determination unit 3 until a transaction for theinserted banknotes is established; a plurality of banknote cassettes 5for performing a recycling function by loading the banknotes inserted bythe customer and providing the loaded banknotes; and a reject box 6 forcollecting a banknote which is significantly damaged or worn among thebanknotes inserted by the customer.

As such, when a banknote inserted by the customer is significantlydamaged or worn, the banknote needs to be separately stored in thereject box so as not to be recycled. Korean Patent Publication No.2016-0077671 has disclosed a banknote processing device that recognizesinserted banknotes to determine the kinds of the banknotes and whetherthe banknotes are counterfeit or whether the banknotes are damaged, andseparately discharges the banknotes to one or two ore more load pocketsinstalled in a discharge unit depending on the determination results.

As disclosed in Korean Patent Publication No. 2016-0077671, the banknoteprocessing device can identify a damaged banknote by determining whethera tape is attached on the banknote through an ultrasonic sensor,detecting a torn or holey banknote through a contact image sensor,detecting a drowned banknote through an ultraviolet sensor, or detectinga banknote covered with scribbles through an infrared sensor.

However, although a banknote has not been damaged, the original color orconcentration of ink printed on the banknote may fade or the banknotemay be worn with time. Such a banknote needs to be separately stored soas not to be withdrawn to a customer. However, there are no techniquescapable of effectively and accurately determining how worn the banknotesare. Therefore, even a banknote which must be determined to be acounterfeit or suspicious banknote or of which the recycling must bestopped may be processed and recycled as a normal banknote.

SUMMARY

Various embodiments are directed to a worn banknote identificationmethod which acquires an image of a banknote inserted into an ATM,divides pixels of the acquired banknote image into a bright region anddark region depending on a brightness distribution of the banknoteimage, determines the wear level of the banknote by comparing adifference between the average brightness values of the two regions to apreset reference value, and separately stores the inserted banknote intoa reject box depending on the wear level of the banknote, and an ATMusing the same.

In an embodiment, there is provided a worn banknote identificationmethod which determines the wear level of a banknote inserted into anATM using an image of the banknote. The worn banknote identificationmethod may include: acquiring an image of the banknote through an imagesensor; calculating brightness values of pixels in the acquired banknoteimage by converting the banknote image into gray scales; extracting athreshold value for determining the variance of the brightness values ofthe pixels in the banknote image; dividing the pixels of the banknoteimage into a bright region and a dark region, based on the extractedthreshold value; calculating a difference between the average brightnessvalues of the two regions by calculating the average brightness value ofthe bright region and the average brightness value of the dark region;and determining whether the corresponding banknote is a worn banknote,by comparing the calculated difference to a preset reference value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a conventional ATM.

FIG. 2 shows images obtained by scanning a new banknote and wornbanknote, respectively, in order to compare the new banknote which hasbeen recently issued to the worn banknote which has been used for apredetermined period or more.

FIG. 3 includes graphs illustrating data obtained by scanning abanknote, wherein image pixels obtained by scanning the banknote areclassified into a bright region, intermediate region and dark regiondepending on the brightness values of the image pixels, in order to showthe changes of the brightness values in the respective regions dependingon the period of use of the banknote.

FIG. 4 is a flowchart illustrating a worn banknote identification methodaccording to an embodiment of the present invention.

FIGS. 5A and 5B are graphs comparatively showing brightness valuedistributions of image pixels obtained by scanning a new banknote whichhas been recently issued and a worn banknote which has been used for apredetermined period or more.

DETAILED DESCRIPTION

The present invention can be modified in various manners and embodied invarious manners. Thus, specific embodiments will be described in detailwith the reference to the accompanying drawings.

However, the present invention is not limited to the specificembodiments, but may include all modifications, equivalents andsubstitutions without departing the scope of the present invention. Theterms such as first and second may be used for describing variouselements, but the elements should not be limited by the terms. The termsare used only for distinguishing from one element from another element.For example, a first element may be referred to as a second element, andthe second element may be referred to as the first element, withoutdeparting from the scope of the present invention.

The terms used in this specification are used only to describe specificembodiments, and do not limit the present invention. The terms of asingular form may include plural forms unless referred to the contrary.In this specification, the meaning of “include” or “have” specifies aproperty, number, step, process, element, part or combinations thereof,but does not exclude one or more other properties, numbers, steps,processes, elements, parts or combinations thereof.

Hereafter, specific embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 shows images obtained by scanning a new banknote and wornbanknote, respectively, in order to compare the new banknote which hasbeen recently issued to the worn banknote which has been used for apredetermined period or more.

Referring to FIG. 2 which comparatively shows the scan images of the newbanknote (a) and the worn banknote (b), a relatively dark-coloredportion of the worn banknote (b) has faded and a relativelybright-colored portion of the worn banknote (b) has darkened due tostains or wrinkles, because the banknote (b) has been used for a longtime. Furthermore, the worn banknote has a lower contrast and edgestrength than the new banknote.

FIG. 3 includes graphs illustrating data obtained by scanning abanknote. In FIG. 3, image pixels obtained by scanning the banknote maybe classified into a bright region, intermediate region and dark regiondepending on the brightness values of the image pixels, in order to showthe changes of the brightness values in the respective regions dependingon the period of use of the banknote.

As illustrated in FIG. 3, the brightness values of the image pixelsobtained by scanning the banknote may be classified into a bright region(a), an intermediate region (b) and a dark region (c), in order tocompare the changes of the brightness values of the respective regionsdepending on the period of use of the banknote. In the bright region(a), the brightness values of the pixels gradually decrease becausestains and wrinkles occur with the continuous use of the banknote. Inthe dark region (b), however, the brightness values of the pixelsgradually increase because the colors thereof fade with the continuoususe of the banknote. Furthermore, in the intermediate region (b), thebrightness values of the pixels do not significantly change despite thecontinuous use of the banknote.

That is, the bright region of the worn banknote becomes darker than thatof the new banknote, and the dark region of the worn banknote becomesbrighter than that of the new banknote. Thus, the variance of the wholebrightness values in the worn banknote becomes smaller than that of thenew banknote. Based on the characteristic that the variance of thebrightness values in the worn banknote becomes smaller than that of thenew banknote, the worn banknote identification method may compare thevariance of the brightness values of image pixels obtained by scanning abanknote, in order to determine how worn the banknote is. For thisoperation, the worn banknote identification method may extract athreshold value for determining the variance of the brightness values ofthe pixels in the banknote image, divide the pixels into a bright regionand a dark region depending on the brightness values thereof based onthe threshold value, calculate a difference between the averagebrightness values of the two regions, and compare the difference to apreset reference value, in order to determine how worn the banknote is.

Hereafter, the worn banknote identification method according to theembodiment of the present invention will be described with reference toFIGS. 4 and 5.

FIG. 4 is a flowchart illustrating the worn banknote identificationmethod according to the embodiment of the present invention.

As illustrated in FIG. 4, the worn banknote identification methodaccording to the embodiment of the present invention begins with stepS410 of acquiring an image of a banknote transferred along a transferpath through an image sensor.

Then, the worn banknote identification method calculates the brightnessvalues of pixels in the acquired banknote image by converting thebanknote image into gray scales at step S420. During the gray scaleconversion of the banknote image, the worn banknote identificationmethod may extract only brightness signals by removing color signalsfrom the acquired banknote image or extract only the brightness valuesof green data in the acquired banknote image, in order to calculate onlythe brightness values of the respective pixels in the banknote image.

Then, the worn banknote identification method extracts a threshold valuefor determining the variance of the brightness values of the pixels inthe banknote image, and divides the pixels of the banknote image into adark region and a bright region, based on the threshold value, at stepS430.

At this time, the publicly-known Otsu thresholding algorithm may be usedto extract the threshold value for determining the variance of thebrightness values of the pixels. The Otsu thresholding algorithm aims tofind a valley and set the valley to a threshold value T, under thesupposition that the histogram shape of an image is bimodal. That is,the Otsu thresholding algorithm generates a graph based on thebrightness values of the pixels in the banknote image, and divides thegraph into two regions based on a threshold value at which the sum ofvariances corresponding to the two regions is minimized. Since the Otsuthresholding algorithm is generally used in image processing, thedetailed descriptions are omitted herein.

Then, the worn banknote identification method calculates the averagebrightness value of the bright region and the average brightness valueof the dark region, based on the threshold value, and calculates adifference between the average brightness values of the two regions, atstep S440. Then, the worn banknote identification method determines howworn the banknote is, by comparing the difference to a preset referencevalue, at step S450.

FIGS. 5A and 5B are graphs comparatively showing distributions of theimage pixels obtained by scanning the new banknote which has beenrecently issued and the worn banknote which has been used for apredetermined period or more.

In FIGS. 5A and 5B, the X-axis indicates values obtained by dividing thebrightness values into 0 to 255, and the Y-axis indicates the numbers ofimage sensor pixels corresponding to the respective brightness values.

As illustrated in FIGS. 5A and 5B, a difference So between the averagebrightness value Do of the dark region and the average brightness valueLo of the bright region in the worn banknote is smaller than adifference Sn between the average brightness value Dn of the dark regionand the average brightness value Ln of the bright region in the newbanknote.

In other words, since the bright region of the worn banknote becomesdarker than that of the new banknote and the dark region of the wornbanknote becomes brighter than that of the new banknote, the variance ofthe brightness values of the respective pixels in the image sensor,which are obtained by scanning each of the banknotes, may decrease.Therefore, with the decrease in variance of the brightness values of thepixels in the banknote image, the difference between the averagebrightness values of the dark region and the bright region decreases.This indicates that, as the banknote is worn, the difference between theaverage brightness values of the dark region and the bright regiongradually decreases.

As such, the worn banknote identification method may extract thethreshold value for determining the variance of the brightness values ofthe respective pixels in the image sensor, which are obtained byscanning the banknote, divide the pixels into the bright region and thedark region depending on the brightness values based on the thresholdvalue, calculate the difference between the average brightness values ofthe two regions, compare the difference to the preset reference value,and determine that the corresponding banknote is a worn banknote whenthe difference is equal to or less than the preset reference value.

More specifically, the worn banknote identification method may convertthe banknote image acquired through the image sensor into gray scales,and detect the brightness values of the respective pixels in thebanknote image, which are classified into a total of L levels from 0 to(L−1). When the threshold value extracted to determine the variance ofthe brightness values of the respective pixels in the banknote image isrepresented by t and the number of pixels having a brightness value of iis represented by n_(i), the difference δ_(t) between the averagebrightness values of the bright region and the dark region in thebanknote image may be calculated as Equation 1 below.

$\begin{matrix}{\delta_{t} = {{\sum\limits_{t}^{L - 1}{i\; {n_{i}/{\sum\limits_{t}^{L - 1}n_{i}}}}} - {\sum\limits_{0}^{t - 1}{i\; {n_{i}/{\sum\limits_{0}^{t - 1}n_{i}}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack\end{matrix}$

At this time, the difference δ_(t) may be defined as ‘wear level’indicating how worn the corresponding banknote is, and compared to thereference value δ_(t) ^(ref) which is preset to define the standard forbanknotes which can be recycled, in order to identify whether thecorresponding banknote is a worn banknote.

That is, the reference value δ_(t) ^(ref) may indicate a minimum wearlevel which is required to determine whether a banknote can be recycled.The reference value δ_(t) ^(ref) may be preset and stored throughprevious scan results for a plurality of worn banknotes. When the wearlevel of an identified banknote is equal to or less than the referencevalue, the corresponding banknote may be determined to be a wornbanknote of which the recycling needs to be stopped.

When the corresponding banknote is determined to be a worn banknotethrough the above-described process, the banknote is separately storedin a reject box at step S460.

As described above, the worn banknote identification method may acquirean image of a banknote inserted into the ATM, divide the pixels of theacquired image into a bright region and a dark region depending on thebrightness distribution of the image, and determine the wear level ofthe corresponding banknote by comparing a difference between the averagebrightness values of the two regions to the preset reference value.Therefore, the worn banknote identification method can effectivelydetermine the wear level of the inserted banknote, and separately storea worn banknote of which the recycling needs to be stopped, into thereject box.

While various embodiments have been described above, it will beunderstood to those skilled in the art that the embodiments describedare by way of example only. Accordingly, the disclosure described hereinshould not be limited based on the described embodiments.

What is claimed is:
 1. A worn banknote identification method whichdetermines the wear level of a banknote inserted into an ATM using animage of the banknote, comprising: acquiring an image of the banknotethrough an image sensor; calculating brightness values of pixels in theacquired banknote image by converting the banknote image into grayscales; extracting a threshold value for determining the variance of thebrightness values of the pixels in the banknote image; dividing thepixels of the banknote image into a bright region and a dark region,based on the extracted threshold value; calculating a difference betweenthe average brightness values of the two regions by calculating theaverage brightness value of the bright region and the average brightnessvalue of the dark region; and determining whether the correspondingbanknote is a worn banknote, by comparing the calculated difference to apreset reference value.
 2. The worn banknote identification method ofclaim 1, wherein the calculating of the brightness values of the pixelsin the banknote image comprises extracting only brightness signals byremoving color signals from the image of the inserted banknote.
 3. Theworn banknote identification method of claim 1, wherein the calculatingof the brightness values of the pixels in the banknote image comprisesextracting only brightness values of green data from the image of theinserted banknote.
 4. The worn banknote identification method of claim1, wherein the extracting of the threshold value comprises extractingthe threshold value using the Otsu thresholding algorithm.
 5. The wornbanknote identification method of claim 4, wherein the extracting of thethreshold value using the Otsu thresholding algorithm comprises findinga valley in a distribution graph of the brightness values of the pixelsand extracting the valley as the threshold value.
 6. The worn banknoteidentification method of claim 1, wherein in the calculating of thedifference between the average brightness values of the two regions,Equation 2 below is applied: $\begin{matrix}{\delta_{t} = {{\sum\limits_{t}^{L - 1}{i\; {n_{i}/{\sum\limits_{t}^{L - 1}n_{i}}}}} - {\sum\limits_{0}^{t - 1}{i\; {n_{i}/{\sum\limits_{0}^{t - 1}n_{i}}}}}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$ where δ_(t) represents the difference between the averagebrightness values of the bright region and the dark region, L representsthe number of brightness value levels, t represents the threshold value,i represents a brightness value, and n_(i) represents the number ofpixels having the brightness value i.
 7. The worn banknoteidentification method of claim 1, wherein in the determining of whetherthe corresponding banknote is a worn banknote, a minimum wear levelrequired to determine whether a banknote is recyclable is preset througha previous scan operation and stored as the reference value, and whenthe calculated difference is equal to or less than the reference value,the corresponding banknote is determined to be a worn banknote.
 8. Aworn banknote identification method which determines the wear level of abanknote inserted into an ATM using an image of the banknote, whereinthe worn banknote identification method comprises extracting a thresholdvalue for determining the variance of brightness values of pixels in thebanknote image acquired through an image sensor, dividing the pixelsinto a bright region and a dark region depending on the brightnessvalues based on the threshold value, calculating a difference betweenthe average brightness values of the two regions, and comparing thedifference to a preset reference value to determine whether thecorresponding banknote is a worn banknote.
 9. The worn banknoteidentification method of claim 8, wherein the extracting of thethreshold value comprises finding a valley in a distribution graph ofthe brightness values of the pixels and extracting the valley as thethreshold value, using the Otsu thresholding algorithm.